写一个功能齐全的富文本器

以下是一个功能齐全的富文本器，支持基本的文字编辑、插入图片、插入链接、插入视频等操作：

HTML 部分：

<div class="editor">
  <div class="toolbar">
    <button class="bold" title="加粗"><i class="fas fa-bold"></i></button>
    <button class="italic" title="斜体"><i class="fas fa-italic"></i></button>
    <button class="underline" title="下划线"><i class="fas fa-underline"></i></button>
    <button class="strike" title="删除线"><i class="fas fa-strikethrough"></i></button>
    <button class="subscript" title="下标"><i class="fas fa-subscript"></i></button>
    <button class="superscript" title="上标"><i class="fas fa-superscript"></i></button>
    <button class="align-left" title="左对齐"><i class="fas fa-align-left"></i></button>
    <button class="align-center" title="居中对齐"><i class="fas fa-align-center"></i></button>
    <button class="align-right" title="右对齐"><i class="fas fa-align-right"></i></button>
    <button class="align-justify" title="两端对齐"><i class="fas fa-align-justify"></i></button>
    <button class="undo" title="撤销"><i class="fas fa-undo"></i></button>
    <button class="redo" title="重做"><i class="fas fa-redo"></i></button>
    <button class="insert-image" title="插入图片"><i class="fas fa-image"></i></button>
    <button class="insert-link" title="插入链接"><i class="fas fa-link"></i></button>
    <button class="insert-video" title="插入视频"><i class="fas fa-video"></i></button>
  </div>
  <div class="content" contenteditable="true"></div>
</div>

CSS 部分：

.editor {
  border: 1px solid #ccc;
  padding: 10px;
}

.toolbar {
  margin-bottom: 10px;
}

.toolbar button {
  border: none;
  cursor: pointer;
  margin-right: 5px;
  background: none;
}

.toolbar button i {
  font-size: 16px;
}

.content {
  border: 1px solid #ccc;
  min-height: 100px;
  padding: 5px;
}

JavaScript 部分：

const boldButton = document.querySelector('.bold');
const italicButton = document.querySelector('.italic');
const underlineButton = document.querySelector('.underline');
const strikeButton = document.querySelector('.strike');
const subscriptButton = document.querySelector('.subscript');
const superscriptButton = document.querySelector('.superscript');
const alignLeftButton = document.querySelector('.align-left');
const alignCenterButton = document.querySelector('.align-center');
const alignRightButton = document.querySelector('.align-right');
const alignJustifyButton = document.querySelector('.align-justify');
const undoButton = document.querySelector('.undo');
const redoButton = document.querySelector('.redo');
const insertImageButton = document.querySelector('.insert-image');
const insertLinkButton = document.querySelector('.insert-link');
const insertVideoButton = document.querySelector('.insert-video');
const content = document.querySelector('.content');

boldButton.addEventListener('click', () => document.execCommand('bold', false, null));
italicButton.addEventListener('click', () => document.execCommand('italic', false, null));
underlineButton.addEventListener('click', () => document.execCommand('underline', false, null));
strikeButton.addEventListener('click', () => document.execCommand('strikethrough', false, null));
subscriptButton.addEventListener('click', () => document.execCommand('subscript', false, null));
superscriptButton.addEventListener('click', () => document.execCommand('superscript', false, null));
alignLeftButton.addEventListener('click', () => document.execCommand('justifyLeft', false, null));
alignCenterButton.addEventListener('click', () => document.execCommand('justifyCenter', false, null));
alignRightButton.addEventListener('click', () => document.execCommand('justifyRight', false, null));
alignJustifyButton.addEventListener('click', () => document.execCommand('justifyFull', false, null));
undoButton.addEventListener('click', () => document.execCommand('undo', false, null));
redoButton.addEventListener('click', () => document.execCommand('redo', false, null));

insertImageButton.addEventListener('click', () => {
  const url = prompt('请输入图片链接地址', 'https://');
  if (url) {
    document.execCommand('insertImage', false, url);
  }
});

insertLinkButton.addEventListener('click', () => {
  const url = prompt('请输入链接地址', 'https://');
  if (url) {
    document.execCommand('createLink', false, url);
  }
});

insertVideoButton.addEventListener('click', () => {
  const url = prompt('请输入视频链接地址', 'https://');
  if (url) {
    const videoHtml = `<video src="${url}" controls></video>`;
    document.execCommand('insertHTML', false, videoHtml);
  }
});

这个富文本器比较全面，支持多种编辑操作，也可以作为一个基础版本，供您进行二次开发。